JPS61195902A - Sintering method of rare earth magnet - Google Patents

Abstract

PURPOSE:To suppress the generation of camber and deformation in the stage of sintering and to prevent the seizure to a base plate, keep plate, etc. in the stage of sintering a thin sheet-shaped green compact molding consisting of rare earth magnet material powder by sintering the green compact molding on many small balls on the base plate. CONSTITUTION:The many small balls 3 are disposed on the base plate 5 and the thin sheet-shaped green compact molding 4 consisting of the rare earth magnet material is imposed thereon; further the small balls 3 are disposed thereon as well and the keep plate 2 is placed thereon. The entire part is put into a Ta foil vessel 6 and a Ta cap 1 is put thereon. The assembly is placed still in an electric furnace and the molding 4 is sintered. Then the seizure arises hardly as the contact area of the molding 4 with the base plate 5 and the keep plate 2 is small in the stage of sintering. Since the small balls 3 have the freedom to move during shrinking of the molding 4, the generation of the nonuniform deformation in the molding 4 is obviated and the camber is effectively suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a method of placing a powder compact made of a rare earth magnet material on a substrate and sintering the compact.

[Background technology]

Rare earth magnets have high saturation magnetization and large holding power, so they have recently been widely used in step motors and various audio equipment, which have strong demands for miniaturization and high performance.
Thin plates are often used. Until now, thin plate magnets have been made by slicing thick blocks to a predetermined thickness, but this was uneconomical as there was a lot of material loss due to cutting allowances, which was a factor in high costs. .

In order to overcome these drawbacks, a method has been considered in which the material is first formed into a thin plate in a magnetic field and then sintered.
When such a thin plate-shaped powder compact is sintered, the compact shrinks during sintering, so as a general method to prevent zero warpage and non-uniform deformation that occur after sintering,
It has been considered to stack a large number of thin plate-like molded bodies or to use a presser plate or the like to prevent deformation.

However, when compacts containing highly reactive materials such as rare earth elements are sintered, the stacked compacts react with each other, or the presser plate used to prevent deformation reacts with the compacts, resulting in some parts It has been difficult to achieve the original purpose due to the occurrence of burn-in, resulting in deformation and unacceptable dimensional errors.

[Purpose of the invention]

In view of the above circumstances, the present invention is aimed at suppressing the occurrence of warping and deformation during sintering when sintering a thin plate-shaped powder compact containing a highly reactive rare earth element, and suppressing the occurrence of warping and deformation of substrates, presser plates, etc. The object of the present invention is to provide a sintering method that does not cause burn-in.

[Disclosure of the invention]

In order to achieve the above object, the present invention arranges a large number of small balls on a substrate on which the powder compact is placed during sintering, in the process of sintering a thin plate-shaped powder compact made of rare earth magnet material powder. The gist of the present invention is a method for sintering a rare earth magnet, which is characterized in that the powder compact is placed thereon and sintered.

This will be explained in detail below.

Rare earth magnet materials used in this invention include R, T,
There is a material represented by Here, R is Sm, Ce, p
It represents rare earth elements such as r, and Mitsushmetal, which is a rare earth combination that is not purified and separated, and T is a so-called transition element, from which rare earth elements have been removed. For example, T i + Fe + Co, Ni, Cu, Zr,
Hf, etc., all of which are composed of one or more types of elements. n and m are represented by arbitrary numbers. Specifically, such materials include SmCo, Sm, Co, ?
, Ce (CoFeCu) s , Sm
(CoFeCuZr)? .

,,Sm (C,oFecu) ,, (SmPr)
C.

, etc., but of course it is not limited to these (,
In short, the sintering method according to the present invention, which only needs to contain rare earth elements, uses a powder compact formed by molding powder of these rare earth magnet materials into a predetermined thin plate shape. The compacted powder is usually formed using a press or the like. The substrate on which the powder compact is placed during sintering is stainless steel (SUS304, etc.),
Mo.

Metal materials such as Ta or Al t Os, Si
It is made of ceramic material such as x Na, and on this substrate is also made of stainless steel (SUS304 etc.).
, Mo, Ta or other metal materials such as AlI3, , Si
Small spheres (balls) made of ceramic materials such as @N, etc.
are arranged in large numbers at a density that allows some movement, and the thin plate-shaped powder compact is placed thereon and sintered.

Furthermore, if necessary, it is also possible to arrange a large number of the same type of small balls on the powder compact and sinter it by placing the same type of presser plate on top. Lamination over layers is also possible. By doing so, you can greatly increase productivity. More favorable results can be obtained by applying slight vibrations during sintering.

This will be explained in detail below based on an example.

(Example 1) As shown in FIG. 1, small balls 3 are arranged on a substrate 5, a thin plate-shaped powder compact 4 of rare earth magnet material is placed on top of the small balls 3, and small balls 3, a press plate 2 was placed thereon, the whole was placed in a tantalum foil container 6, and a tantalum lid 1 was placed thereon. Note that FIG. 1 only shows the basic configuration of the arrangement of the substrate, small balls, etc., and the shape, dimensions, etc. are not restricted thereto.

The rare earth magnet material used had a basic composition of Sm(C.

It is a powder consisting of FeCuZr)t, s, which is compacted into a thin disk shape with a diameter of 45 mm and a thickness of 1.2 m (green density is about 4.4 g/-), the substrate 5 and the presser. Board 2 is both 50 Tsuru Kaku.

Substrate 5 is a stainless steel plate (SUS304) with a thickness of l■
The small balls placed on the powder compact 4 were stainless steel poles (SUS304) with a diameter of 1 square inch, and were allowed to move relative to each other.

In other words, the number of pieces used was such that a slight gap could be provided. Next, these were placed in a tantalum foil container 6 with an inner dimension of 50 square square inches, covered with a tantalum lid 1 of 51 square square square square inches, and placed in an electric furnace. After reducing the pressure for a while, argon gas was introduced into the furnace and heated to 1100-1200°C in a non-oxidizing atmosphere.
After heating for 1 hour and sintering, solution treatment was performed at 1050 to 1150°C for 2 hours, and then rapidly cooled.

The density after sintering was about 8.4 g/-, and the dimensions were 36 fi in diameter and 0.95 in thickness. At this time, the degree of deformation 9 Warpage, seizure, and crack occurrence were compared with the case where stainless steel balls were not used and only the holding plate was used (comparative example). The results are shown in Table 1. .

Table 1 (Note) Roundness: Maximum diameter - Minimum diameter Circularity: In the example shown by h in Figure 2, the degree of deformation is clearly better than that of the comparative example, and there is no seizure or cracking. It is also excellent in that it does not cause the occurrence of It should be noted that the warpage was very slight in both cases.

(Example 2) During sintering, slight vibration was applied for 10 minutes after the start of sintering.
The rest was the same as in Example 1.

Table 1 shows the degree of deformation 9, the presence or absence of warping, seizure, and crank occurrence at this time. Adding micro-vibration facilitates the movement of the globules and suppresses non-uniform deformation, resulting in even better results in terms of roundness.

〔Effect of the invention〕

The sintering method according to the present invention has the above configuration, and the contact area between the powder compact and the substrate or presser plate is small during the sintering process. If the small spheres have the freedom to move when the body contracts during sintering, no external force is applied to partially suppress the contraction, so uneven deformation does not occur and warping is effectively prevented. It can be suppressed. Therefore, according to the present invention, it is possible to obtain a thin plate-shaped rare earth magnet with a high manufacturing yield.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the present invention, and FIG. 2 is a side view showing a method for measuring warpage. 2... Holding plate 3... Small ball 4... Green compact of rare earth magnet 5... Substrate representative Patent attorney Takehiko Matsumoto Figure 1 Nage-zuke --〆π

Claims (3)

[Claims] (1) In the step of sintering a thin plate-shaped powder compact made of rare earth magnet material powder, a large number of small balls are arranged on a substrate on which the compact is placed during sintering, and the compacted powder is placed on top of the substrate. A method for sintering rare earth magnets, which is characterized by sintering a rare earth magnet by placing a body thereon. (2) A method for sintering a rare earth magnet according to claim 1, wherein a large number of small balls are also arranged on the compacted powder body, and a presser plate is placed thereon for sintering. (3) A method for sintering a rare earth magnet according to claim 1 or 2, which provides slight vibrations during sintering.